Here are some nice instructions with pictures.
Removing z4 roof.
At around 18 minutes when screwing in the hydraulic line bolts back into the motor tighten these two bolts up to manufacturers spec.
08 10 2018 11 49 am by momo1 i need your guys help on removing the roof lining i have searched quite a bit and haven t had any joy.
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Pull this ring pull out by about 1 4 and turn it through 90 degrees and this will lock the hydraulic bypass valve in the open position this will then let you lower the roof by hand.
A replacement motor was a cool 350 plus a new housing and hydraulic repair kit bringing the total to 450.
Momo1 officially a forum statistic.
Replacing the motor involves removing the entire roof assembly which is a fiddly and laborious job and is an expensive option if you are going to get this done at an indy garage.
E86 z4 coupe roof lining removal.